Crankcase reculating system



25, 1954 J. M. BARR ETAL CRANKCASE REGULATING SYSTEM Filed July 2, 1963 0 m H o m m5 r w 4 ad e n w M w United States Patent 3,145,697 CRANKCASE REGULATING SYSTEM John M. Barr and Howard H. Dietrich, Rochester, N.Y., assignors to General Motors Corporation, Detroit, Mich,. a corporation of Delaware Filed July 2, 1963, Ser. No. 292,324 4 Claims. (Cl. 123-119) This invention relates to the ventilation of crankcases of internal combustion engines; and more particularly to a system for regulating the pressure of crankcase vapor in an internal combustion engine.

In the design and operation of internal combustion engines it is desirable to provide a ventilation system for the engine crankcase for positive removal of and protection from crankcase fumes. At the same time, it is desirable to prevent such fumes from passing to the atmosphere and contributing to the creation of objectionable smog or the like. In the past, crankcase ventilating systems have been provided which circulate air through the crankcase by providing inlet and outlet means at such points that a difference of atmospheric pressure exists between these points when the engine is being operated. The vapor pressures in the crankcase are generally regulated in some manner so as to maintain a subatmospheric pressure in the crankcase to draw in fresh air from a convenient source. The regulating means usually passes the fumes from the crankcase to the engine intake manifold to mix the crankcase fumes with the incoming fuel and air charge to the engine cylinders and thus burn any unburned hydrocarbons and otherwise consume the crankcase fumes. However, it has been discovered that under abnormal engine operating conditions, when the intake manifold vacuum is very low, pressures will build up in the engine crankcase which may have adverse effects on the operation of the engine and a detrimental effect on the parts of the engine. Piston blow-by, for example, will increase the crankcase pressures, particularly at times during which the engine is operated at high load and low speeds.

The device in which this invention is embodied comprises, generally, a crankcase regulating system utilizing a regulator valve assembly which is operable to maintain a subatmspheric pressure in the engine crankcase during normal operation of the engine. A second valve assembly located at the fresh air inlet to the engine includes a relief valve which is calibrated and operable to relieve the excessive or abnormal pressures in the engine crankcase during the periods of abnormal operation of the engine. The relief valve assembly includes a calibrated inlet orifice which permits clean fresh air to be circulated through the engine at all times to replace crankcase fumes and gases which are normally passed to the inlet manifold.

With the relief valve assembly in the system the adverse effects of crankcase pressure build-up during abnormal operation of the engine will be eliminated. Clean fresh air will continue to circulate through the engine and the crankcase pressures will be regulated during normal operation. When the intake manifold vacuum is very low, such as during high load and low speed of the engine, piston blowby and other pressure build-ups will be relieved through the relief valve assembly.

These and other advantages will become more apparent from the following description and drawing, in which:

FIGURE 1 is a partly diagrammatic and partly sectional view of an internal combustion engine showing the regulator valve assembly and the relief valve assembly in enlarged cross-section; and

FIGURE 2 is a cross-sectional view of the relief valve member taken substantially along the line 22 of FIG- URE l and looking in the direction of the arrows.

Referring more particularly to the drawing, FIGURE 1 best illustrates the internal combustion engine, illustrated 3,145,697. Patented Aug. 25, 1964 "ice generally by the numeral 10, as well as the over-all system. Engine 10 is a typical V8 internal combustion engine having a cylinder block 12, a pair of cylinder heads 14 and 16 supported on the block 12 and which are covered in the usual manner by rocker arm covers 18 and 26, respecticely. An intake manifold 22 joins the cylinder heads 14 and 16 and supports a usual carburetor 24 and an inlet air cleaner, not shown. At opposite edges of the cylinder heads 14 and 16 are suitable exhaust manifolds 32 and 34 which convey the burned products of combustion from the combustion chambers to the atmosphere. Closing the bottom of the cylinder block 12 is the usual oil pan 26. A crankshaft 28 is journalcd in the cylinder head 12 in the usual manner and drives a camshaft 30 for the operation of the valves in the cylinder heads 14 and 16. The volume of the engine around the crankshaft 28 and within the oil pan 26 is commonly referred to as the engine crankcase.

In order to regulate the pressures in the engine crankcase and as part of the engine ventilating system, a crankcase regulator assembly, illustrated generally by the numeral 36, is provided. Regulator assembly 36 is disposed between conduits 38 and 40 which communicate between the engine crankcase and the intake manifold 22. The crankcase regulator assembly 36 includes a housing 42 having a bore 44 formed therein and which suitably receives the end of conduit 38. The upper end of housing 42 is provided with a radial flange 46 to which is secured a sheet metal closure member 48. Closure member 48 is secured to housing 42 by means of a spring wire bail or the like 50 and is provided with a calibrated orifice 52 for purposes to be later described. Clamped between the closure member 48 and the housing flange 46 is a resilient diaphragm 54 sandwiched between rigidifying plates 56 and 58. The diaphragm 54 divides the chamber defined by the closure member 48 and the housing 42 into an atmospheric chamber 60 and a crankcase pressure chamber 62. The orifice admits air at atmospheric pressure to the chamber 60 and thus to the upper side of the diaphragm 54.

Reciprocably disposed in the bore or passage 54 is a valve member 64 secured in any suitable manner to the diaphragm 54, as by rivet or bolt 66. Valve member 64 has a central bore 68 formed partially therethrough, and a calibrated orifice 70 communicates between the passage 68 and the crankcase pressure chamber 62 at the lower side of the diaphragm 54. Thus, direct communication is established between the engine crankcase and the diaphragm chamber 62. A calibrated spring 72 engaging the underside of sandwich plate 58 and at its other end engaging a spring seat 74 mounted in housing 42, biases the diaphragm 54 and valve member 64 outwardly against the atmospheric pressure in chamber 60.

A cross passage 76 in housing 42 communicates with the passage 44 in the housing and opens out to receive the conduit 40 extending to the intake manifold 22 of the engine 19. Disposed within passage 76 is an annular screen member 78 which serves to prevent backfire explosions from reaching the engine crankcase and causing harmful damage.

Under normal operating conditions of the engine 10 atmospheric pressure will obtain in the chamber 60 above diaphragm 54 entering the chamber 60 through the metered orifice 52. Crankcase pressure through the conduit 38 and the passage 44 will obtain in the lower diaphragm chamber 62 through the passage 68 and metered orifice 70 in the valve member 64. Intake manifold vacuum through the conduit 49 acts on the crankcase fumes to draw the fumes into the intake manifold and thus to the combustion chambers in the engine. A subatmospheric pressure will always be maintained within the engine crankcase. The desired amount of vacuum will be maintained by virtue of the size of the diaphragm 54, the rate of the calibrated spring 72 and the size of the metering orifice 70. When these parameters are properly set the de sired subatmospheric pressure will be maintained in the engine crankcase and a vacuum of from five to two inches of water is preferred. As pressures change and as diaphragm 54 moves upwardly or downwardly against the spring 72 and against the crankcase pressure, valve member 64 will gradually open or close the passage 76 to the manifold conduit 40 to modulate the fiow of crankcase fumes to the intake manifold. When manifold vacuum is exceedingly low, as during high load and slow speed operation of the engine, the valve member 64 will be caused to substantially close the passage 76 to the intake manifold, and it is during these periods of operation that pressures may build up in the engine crankcase.

In order to provide relief for pressure build-up in the crankcase a relief valve assembly, illustrated generally by the numeral 80, is provided. Valve assembly 80 may be disposed in the usual breather tube 82 normally communicating with the rocker arm cover 18 of the engine. The breather tube 82 admits fresh air to the rocker arm cover 18, and thus through the internal engine openings and passages the clean air finds its Way to the engine crankcase.

Relief valve assembly 80 is shown in FIGURE 1 to include an outer housing 84 having a retention strap 86 and a leaf spring 88 for securing the housing 84 within the tube 82. An annular ring 90 disposed in the housing receives the retaining means 86-88 to frictionally maintain the housing 84 in the tube 82. A gasket member 91 may be disposed between the housing 84 and the upper end of tube 82 if desired.

Disposed within the housing 84 is a filter element 92 which may be formed of polyurethane foam or any other suitable material. A second annular filter member 94 of similar material is also provided and which includes a chamber or opening 96 for purposes to be later described. The filter elements 9294 are held in place in the housing 84 by a triangular retainer member 98 received in a rolled groove 100 formed in the upper edge of the housing 84.

The opposite edge of the housing 84 is inwardly formed, as at 102, to provide an annular valve seat for a valve plate 104 received on the valve seat 102 and lightly held in place by the filter elements 92 and 94. Valve plate 104 is provided with a metered orifice 106 which permits the free flow of a predetermined amount of fresh air, filtered by the filter elements 92 and 94, to pass to the breather tube 82. This permits replacement of crankcase fumes and gases with fresh air as the fumes and gases are consumed in the inlet manifold and combustion chambers.

During those periods of high load-low speed operation of the engine, when the regulator valve assembly 36 is substantially closed and pressures build up in the engine crankcase, it is seen that such pressures acting through the internal passages and openings in the engine and to the breather tube 82 cause the valve plate 104 to lift off the seat 102 formed in the housing 84 and exhaust through the filter elements 92 and 94 to the atmosphere. This permits a blow-off or relief of the pressures built up in the engine crankcase and eliminates the possibility of damage to the engine from these abnormal pressures. The pressure of the filter elements 92 and 94 and the size of the metered orifice 106 may be so designed as to permit the valve plate 104 to lift from its seat at approximately one-quarter inch of water pressure. The construction may be such as to permit any other value of pressure to lift the valve plate 104 and relieve the crankcase pressures.

Thus, a crankcase regulating system is provided which eliminates the problems of excessive pressure increase in the engine crankcase during other than normal operation of the engine. During such normal operation crankcase pressures are maintained at a desired subatmospheric value to permit free ventilation of the engine and to prevent the crankcase fumes and gases from exhausting to the atmosphere in their obnoxious condition. At such time as pressures build up in the engine crankcase, means are provided for relieving these presures without adding to the expense or size of the engine parts and in material and equipment which is easily installed on present internal combustion engines.

What is claimed is:

l. Crankcase regulating means for an internal conibustion engine having a crankcase and an inlet manifold and comprising:

conduit means between said inlet manifold and said crankcase;

a regulator valve assembly in said conduit means and operable to maintain a subatmospheric pressure in said crankcase during normal operation of said engine;

and fresh air inlet means for supplying air to said crankcase, said air inlet means including a housing containing a filter element and a valve plate, said valve plate having a calibrated orifice formed therein to permit passage of a predetermined amount of air therethrough and into said crankcase and being biased in valve closed position by said filter element, said valve plate being adapted to open when abnormal pressures are created in said crankcase to relieve said abnormal pressures.

2. Crankcase regulating means for an internal combustion engine having a crankcase and an inlet manifold and comprising:

communication means between said crankcase and said intake manifold and adapted to convey crankcase vapors to said intake manifold;

regulator valve means in said communication means and operable to modulate the flow of crankcase vapors in accordance with the pressure differential between said crankcase and the atmosphere and to maintain said crankcase at subatmospheric pressure during normal operation of said engine;

and fresh air inlet and pressure relief means communieating with said crankcase, said means having a normally closed valve member operable to open when abnormal pressures are created in said crankcase and relieve said abnormal pressures.

3. In combination with an internal combustion engine having a crankcase and an inlet manifold and a regulator valve assembly for maintaining a subatmospheric pressure in said crankcase during normal operation of said engine, fresh air inlet and pressure relief means for said crankcase comprising:

a conduit secured in said engine and communicating with said crankcase;

a housing removably secured in the end of said conduit and having a valve seat therein;

a filter element secured in said housing and, adjacent said valve seat;

and a valve plate in said housing and normally biased into closed position on said valve seat by said filter element, said valve plate having an orifice therein for permitting a predetermined amount of air flow therethrough and to said conduit, said valve plate being adapted to lift off said valve seat when abnormal pressures obtain in said crankcase to relieve said abnormal pressures and protect said engine.

4. In combination with an internal combustion engine having a crankcase and an inlet manifold and a regulating valve assembly for maintaining a subatmospheric pressure in said crankcase during normal operation of said engine, fresh air inlet and pressure relief means for said crankcase comprising:

a conduit received in said engine and communicating with said crankcase;

a housing removably secured in the end of said conduit and having a valve seat formed therein;

a filter element secured in said housing for filtering fresh air passing through said housing and into said conduit;

and a valve member received on said valve seat and held thereagainst by said filter element, said valve member having a flow controlling orifice therein communicating with said conduit and permitting the flow of filtered air through said valve member, said valve member being operable to open when abnormal pres- References Cited in the file of this patent UNITED STATES PATENTS Lowther Oct. 3, 1944 Foster July 8, 1947 

1. CRANKCASE REGULATING MEANS FOR AN INTERNAL COMBUSTION ENGINE HAVING A CRANKCASE AND AN INLET MANIFOLD AND COMPRISING: CONDUIT MEANS BETWEEN SAID INLET MANIFOLD AND SAID CRANKCASE; A REGULATOR VALVE ASSEMBLY IN SAID CONDUIT MEANS AND OPERABLE TO MAINTAIN A SUBATMOSPHERIC PRESSURE IN SAID CRANKCASE DURING NORMAL OPERATION OF SAID ENGINE; AND FRESH AIR INLET MEANS FOR SUPPLYING AIR TO SAID CRANKCASE, SAID AIR INLET MEANS INCLUDING A HOUSING CONTAINING A FILTER ELEMENT AND A VALVE PLATE, SAID VALVE PLATE HAVING A CALIBRATED ORIFICE FORMED THEREIN TO PERMIT PASSAGE OF A PREDETERMINED AMOUNT OF AIR THERETHROUGH AND INTO SAID CRANKCASE AND BEING BIASED IN VALVE CLOSED POSITION BY SAID FILTER ELEMENT, SAID VALVE PLATE BEING ADAPTED TO OPEN WHEN ABNORMAL PRESSURES ARE CREATED IN SAID CRANKCASE TO RELIEVE SAID ABNORMAL PRESSURES. 